1. Field of the Invention
The present invention relates to system and method of supporting connections of a plurality of radio frequency identification (RFID) readers, and more particularly, to RFID middleware system and method of balancing the load occurring while the RFID middleware is running in real-time so as to improve the performance of the RFID middleware system.
2. Description of the Related Art
A Radio Frequency Identification (RFID) technology, which is a non-contact type radio identification technology, provides a network management mechanism and thus is regarded as the main technology in ubiquitous computing. Also, applied fields of the RFID technology are being widely expanded in various areas such as distribution, physical distribution, transportation, finance, and environment under the control of EPCglobal, which is an organization set up to achieve world-wide standardization.
In general, a RFID system includes a RFID tag including a product ID and additional information about the product, a RFID reader for recognizing the RFID tag, and RFID middleware for filtering the recognized tag and delivering the result of the filtering to an upper-level application (client).
In the RFID system, a great number of RFID readers may be installed in large-scale applications such as transportation distribution, storage management, and warehouse management for covering a wide range of reading areas, and various RFID readers may be installed and operated at the same reading spot for improving the recognition rate for a large amount of products. Here, if a plurality of RFID middleware is operated, an operating cost may increase so that as many RFID readers as possible are to be connected to one RFID middleware.
In this case, the RFID middleware may decrease the performance of the entire system due to an increase of costs needed to process not only the load occurring due to management of the various RFID readers but also a large amount of tag data transmitted from each of the RFID readers to the RFID middleware.
Accordingly, a RFID middleware system including a reader framework for managing the RFID readers has been introduced. The reader framework includes adaptors and an adaptor manager, wherein the adaptors actually communicate with physical readers and the adaptor manager manages various adaptors. The adaptors in the system are managed by using one or more threads. In addition, as connected readers increase, the number of adaptors also increases. Thus, the load of the threads used to manage the adaptors may increase. The load of the threads may occur in both adaptor manager and adaptors. In this case, processing of the corresponding threads may be delayed and thus the performance of the RFID middleware decreases.
The threads are used for the adaptors and the adaptor manager to actively process data directly after receiving the data from the readers and the adaptors. Here, since a middleware engine and various adaptors communicate messages with each other, the adaptor manager uses a separate thread. Also, various adaptors exist according to the number of RFID readers connected to the RFID middleware so that a thread model for managing the adaptors needs to be defined.
There are two methods used to manage threads for the adaptors in the RFID middleware system.
First, a multithread model for allocating the threads to each of the adaptors is used. In the multithread model, threads that are exclusive to the adaptors are respectively allocated to the adaptors so that receiving of tag data from the readers and processing of the data may be rapidly performed. However, when the number of the connected readers increases, the number of threads also increases. Accordingly, excessive threads are generated and thus the performance of all threads existing in the system is decreased.
Second, a single thread model is used. In the single thread model, all adaptors are managed by one thread. Unlike the multithread model, operation of all adaptors is managed by one thread in the single thread model and thus an increase of the readers does not affect an increase of the threads. Thus, a large number of readers may be connected to the RFID middleware. However, as the number of adaptors increases, an amount of tag data to be processed by a common thread increases. Thus, generation of a large amount of tag data from a specific adaptor may affect the processing of tag data by all adaptors.